Halogenated Wax Grafted To Low Molecular Weight Polymer

ABSTRACT

A wax-polymer compound includes (a) a polymer component that is a polymerized unsaturated monomer, optionally copolymerized with a vinyl-aromatic monomer, and (b) a halogenated hydrocarbon wax component. The polymer component is grafted to the halogenated hydrocarbon wax component, and the wax-polymer compound has a number average molecular weight of about 1,000 to about 100,000. A method of making the wax-polymer compound and a coated silica particle are also disclosed.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.15/540,882, which on Jun. 29, 2017, entered the U.S. as a national stageapplication of PCT Application No. PCT/IB2015/002538 filed Dec. 22,2015, which claims the benefit of priority to both U.S. ProvisionalApplication No. 62/098,669 filed Dec. 31, 2014, and U.S. ProvisionalApplication No. 62/098,690 filed Dec. 31, 2014. Each of these priorapplications is incorporated herein by reference.

FIELD

This disclosure relates to a halogenated wax-grafted to a low molecularweight polymer.

BACKGROUND

Hydrocarbon waxes have been used in rubber compositions to improvecertain properties of the composition. In applications such as tires,wax has been used as an antiozonant. Chemical attack by ozone is thoughtto be one of the main causes of aging and deterioration of tiresEffective waxes protect the rubber from ozone attack by migrating to thesurface and forming a protective film on the tire. Waxes are also nottypically thought of as improving the performance characteristics of thetire, such as traction or wear resistance.

Rubber compositions traditionally are made with aromatic processing oil,which enables the rubber compositions to be softened and more easilyprocessed. Aromatic oil used in tire tread compositions can provide thetread rubber with improved traction over a composition with no oil.However, some European countries have passed regulations to limit theamount of aromatic oil or polycyclic-aromatic containing oil used in therubber compositions. Many cost-effective substitutes for aromatic oil,such as synthetic ester oils and hydrogenated aromatic oils, do notprovide the same beneficial properties imparted by traditional aromaticoils.

SUMMARY

The present application describes a grafted wax and low molecular weightpolymer that, in embodiments, provides synergistic benefits in rubbercompositions.

In an embodiment, a wax-polymer compound includes (a) a polymercomponent that is a polymerized unsaturated monomer, optionallycopolymerized with a vinyl-aromatic monomer, and (b) a halogenatedhydrocarbon wax component. The polymer component is grafted to thehalogenated hydrocarbon wax component, and the wax-polymer compound hasa number average molecular weight of about 1,000 to about 100,000.

In an embodiment, a method for making a wax-polymer compound includesmixing (a) a polymer component that is living or functionalized, andthat is a polymerized unsaturated monomer, optionally copolymerized witha vinyl-aromatic monomer, and (b) a halogenated hydrocarbon waxcomponent. The polymer component is grafted to the halogenatedhydrocarbon wax component, and the wax-polymer compound has a numberaverage molecular weight of about 1,000 to about 100,000.

In an embodiment, a coated silica composition includes silica coatedwith a wax-polymer compound. The wax-polymer compound includes (a) apolymer component that is a polymerized unsaturated monomer, optionallycopolymerized with a vinyl-aromatic monomer, and (b) a halogenatedhydrocarbon wax component. The polymer component is grafted to thehalogenated hydrocarbon wax component, and the wax-polymer compound hasa number average molecular weight of about 1,000 to about 100,000.

DETAILED DESCRIPTION

In an embodiment, a low molecular weight polymer is grafted with ahalogenated hydrocarbon wax. The wax-polymer compound was surprisinglyfound to exhibit unique properties in a rubber composition that includescarbon black or silica filler and optionally other additives. Inparticular, properties useful in tire components were found to beimproved, including wet traction, wear resistance upon aging, increasein bound rubber and Mooney viscosity comparable or lower than thatprovided by oil. Different beneficial effects were found in carbon andsilica compounds, indicating that the wax-polymer additive was producinga synergistic interaction with the filler, instead of simply providingeffects of a typical wax and low molecular weight polymer/oil.

Without being bound to theory, it is believed that the wax-polymeradditive has one or more of the following types of interaction in afilled rubber composition. (1) The wax-polymer additive is dispersed inand interacts with other components of the polymer matrix, includingfiller and high molecular weight elastomer. (2) The wax-polymer additiveblooms to the surface of the composition providing surface modification.(3) The wax-polymer additive interacts with and coats the filler, actingas a shielding agent. In this case, some of coated filler may alsomigrate to the surface of the composition.

In an embodiment, the wax-polymer additive includes: (a) a polymercomponent that is a polymerized unsaturated monomer, optionallycopolymerized with a vinyl-aromatic monomer, and (b) a halogenatedhydrocarbon wax component. The terms “polymer component” and“halogenated hydrocarbon wax component” are meant to indicate that thepolymer and wax are components of a grafted compound; however, indetermining molecular weight or other properties of each component,determinations of these properties may be made based on the polymer orwax prior to the grafting reaction.

In an embodiment, the wax is halogenated in multiple locations along thehydrocarbon backbone of the wax, and the wax-polymer additive derivedfrom the halogenated wax has a structure with the wax component forminga backbone of the additive and the polymer component forming one or moregrafted branches or “brushes” extending from the backbone. In anembodiment, the wax component may include halogen groups that were notsubstituted.

In an embodiment of the grafting reaction, an unsaturated unit of thepolymer component displaces a halogen on the wax component. The locationof the displaced halogen on the wax may thus be referred to as a graftlocation. In an embodiment, several units of unsaturation on a singlepolymer chain react with and create a bond to multiple graft locationsof the halogenated wax component resulting in multiple halogen leavinggroups. In an embodiment, two or more polymer chains of the polymercomponent bond to two or more graft locations on the halogenated waxcomponent. In an embodiment, the wax-polymer additive has a ratio of thehalogenated hydrocarbon wax to the polymer of about 1:1 to about 1:20,such as, for example, about 1:2 to about 1:15, or about 1:4 to about1:10.

In an embodiment, the wax-polymer additive may be included in the rubbercomposition in an amount of about 0.1 phr to about 60 phr, such as, forexample, about 1 phr to about 10 phr, or 5 phr to about 30 phr.

The wax may be grafted to the low-molecular weight polymer by dissolvingthe polymer or polymerizing the polymer in a hydrocarbon solvent, suchas a non-polar solvent, for example, hexane, in a container. In anembodiment, the polymerized low-molecular weight polymer is notterminated and has a living end when mixed with the halogenated wax. Thehalogenated wax, which may be pre-dissolved in hydrocarbon solvent, suchas a polar solvent, for example, tetrahydrofuran, is also added to thecontainer. In an embodiment, the live end of the polymer reacts with thehalogenated wax by substituting for halogen leaving groups. In anotherembodiment, the polymer is functionalized with a group that will reactwith the chlorinated wax, For example, the functional group may be ahalogen, oxygen, nitrogen, or silicon containing group. The contents ofthe container are then mixed and/or heated. The reaction may then beterminated with a terminating agent, such as butylated hydroxytoluene(BHT) in isopropanol. BHT may stabilize the polymer and reduce gelcontents. However, other functional and/or non-functional terminatingagents may be used. The contents of the container may then becoagulated, such as with an alcohol, and dried by conventional methods.

In an embodiment, and without being bound by theory, a chlorinated waxis modified with a low-molecular weight polymer by the reaction formulaI:

Reaction formula I is an example only. Other embodiments may differ inhalogen, carbon chain, and grafting and functional group locations.

In an embodiment, the low molecular weight polymer may be synthesizedand grafted in the same container without an intermediate isolation orseparation step. The synthesis in this case, may be solutionpolymerization, such as living solution polymerization, for example,anionic or cationic living polymerization. Optionally a randomizer isadded to randomize the monomer addition of the polymer to make randomcopolymers instead of block copolymers.

The wax and the polymer from which the grafted-wax additive are derivedare discussed in more detail below.

In an embodiment, the low molecular weight polymer is derived from atleast one unsaturated monomer, such as a diene monomer. In anembodiment, the polymer is derived, for example, from the polymerizationof one or more of the following conjugated diene monomer units1,3-butadiene, isoprene, 1,3-pentadiene, 1,3-hexadiene,2,3-dimethyl-1,3-butadiene, 2-ethyl-1,3-butadiene,2-methyl-1,3-pentadiene, 3-methyl-1,3-pentadiene,4-methyl-1,3-pentadiene, and 2,4-hexadiene.

In certain embodiments, suitable diene polymers and diene copolymersused in the tire rubber compositions disclosed herein can be derivedfrom the polymerization of one or more of the conjugated diene monomersdisclosed above and one or more vinyl aromatic hydrocarbon monomers.Examples of suitable vinyl aromatic hydrocarbon monomers include, butare not limited to styrene, α-methylstyrene, p-methylstyrene,o-methylstyrene, p-butylstyrene, vinylnaphthalene, and combinationsthereof.

Examples of suitable conjugated diene polymers and conjugated dienecopolymers for use as the polymeric component of the wax-polymeradditive include, but are not limited to, polyisoprene, polybutadiene,butadiene-isoprene copolymer, butadiene-isoprene-styrene copolymer,isoprene-styrene copolymer, styrene-butadiene copolymer, natural rubber,butyl rubber, halogenated butyl rubber, and combinations thereof. In anembodiment, the rubber compositions comprise a combined amount of 100phr of the at least one conjugated diene polymer or copolymer.

In certain embodiments, the diene polymer or copolymer (as describedabove) within the rubber composition is functionalized with a functionalchemical group at one end, both ends, or along the backbone of thepolymer or copolymer. In certain embodiments, the conjugated dienepolymer or copolymer is functionalized or coupled with a tin orsilica-containing compound such as with tin tetrachloride, dibutyl tinchloride, or with another suitable compound, non-limiting examples ofwhich include cyclic amines, polyisocyanates, cyclic ureas, a silylchloride, polyisocyanates, carbodiimides, polyepoxides, andalkoxysilanes.

In an embodiment, the polymer component has a low molecular weight, andis a liquid at 25° C. A number average molecular weight of the polymermay, for example, range from about 500 to about 20,000, such as about1,000 to about 15,000, or about 2,500 to about 8,000. In an embodiment,the polymer may have a vinyl content of about 10% to about 90%, such asabout 15% to about 50%, or about 20% to about 40%. In an embodiment, thepolymer may have a vinyl aromatic hydrocarbon content of about 5% toabout 45%, such as about 10% to about 40%, or about 15% to about 35%. Inan embodiment, the polymer may have a glass transition temperature ofabout −10° C. to about −115° C., such as about −20° C. to about −55° C.,or about −95° C. to about −108° C. If the polymer is a copolymer, it maybe random, tapered, or block.

In an embodiment, the halogenated wax is halogenated version of amicrocrystalline wax or paraffin wax. Paraffin waxes are generallyunbranched C₂₀ to C₄₀ alkane waxes. Microcrystalline waxes arehydrocarbon waxes that generally have a higher percentage ofisoparaffinic and naphthenic groups than paraffin waxes and also have asmaller crystalline structure as compared to the paraffin waxes. Theweight percent of halogenation of the wax may vary from about 0.1 toabout 75%, such as, for example, about 25% to about 75%, or about 50% toabout 71%. The hydrocarbon chain may be branched or unbranched. A ratioof carbon atoms to halogen atoms may range from about 1:1 to about 1:50,such as about 1:2 to about 1:25, or about 1:5. The carbon chain lengthof the wax, may, for example, range from 8 to 50 carbon atoms; it may,for example, be a short chain (C₁₀₋₁₃), medium chain (C₁₄₋₁₇), or longchain, (C_(>17)). The halogen group may be selected from one or more ofthe group consisting of chlorine, fluorine, iodine, or bromine.

In an embodiment, the halogenated wax is a solid, for example, at 0° C.or 25° C., and has a softening point of about 30° C. to about 150° C.,such as about 75° C. to about 125° C., or about 90° C. to about 110° C.(ASTM D-36). The halogenated wax may have a particle size correspondingto passage of about 80 to about 99% through 297 Micron mesh, such asabout 90 to about 97.5%, or about 92.5 to about 96%. The halogenated waxmay have a number average molecular weight of about 200 to about 5,000,such as, for example, about 500 to about 4,000, or about 1,000 to about3,500.

Suitable types of chlorinated hydrocarbon waxes for use in the rubbercompositions disclosed herein include hydrocarbon waxes having achlorocarbon segment, e.g., hydrocarbon segments in which some or allhydrogens have been replaced with chlorine atoms along the carbon chain.In certain embodiments, the chlorinated hydrocarbon wax is a chlorinatedparaffin wax. Suitable, but non-limiting, examples of chlorinatedhydrocarbon waxes suitable for use in the rubber compositions disclosedherein include. Notably, as used herein, the term chlorinatedhydrocarbon wax should be considered to include compounds that aresolids at room temperature and compounds that are oils at roomtemperature, unless it is clear from the context that only compoundsthat are solid at room temperature are intended.

Accordingly, because suitable chlorinated hydrocarbon waxes that areutilized may contain varying amounts of chlorine, it should beunderstood that the total amount of chlorination added to the rubbercomposition can be varied by adjusting the amount (phr) of chlorinatedhydrocarbon wax added to the rubber composition and/or the chlorinecontent of the chlorinated hydrocarbon wax added to the rubbercomposition. Therefore, the total amount of chlorination added to therubber composition may vary from about 0.005 to about 7.5 phr (partschlorine per hundred parts rubber in the rubber composition). In certainembodiments utilizing chlorinated hydrocarbon wax, the amount ofchlorination added to the rubber composition is from about 1 to about 4phr, or about 1.5 to about 3 phr.

Suitable types of fluorinated hydrocarbon waxes for use in the rubbercompositions disclosed herein include hydrocarbon waxes having aperfluorocarbon segment, e.g., a hydrocarbyl segment in which allhydrogens have been replaced with fluorine atoms along the carbon chain.An example of this type of wax is a block copolymer having aperfluorocarbon block segment and a hydrocarbon block segment. Incertain embodiments of this type of fluorinated wax, the block copolymeris represented by the general formula F₃C—(CF₂)_(m)—(CH₂)_(n)—CH₃, wherem is an integer ranging from 1 to about 40, n is an integer ranging fromabout 3 to about 40, and n+m must be greater than about 18. Thus, in oneembodiment, the fluorinated hydrocarbon wax used in the rubbercompositions disclosed herein is a block copolymer having aperfluorocarbon block segment and a hydrocarbon block segment.

In certain embodiments of rubber compositions disclosed herein, thehydrocarbon segment of the fluorinated wax is a paraffin segment, i.e.,an unbranched alkane chain having from about 20 to about 40 carbonatoms. Thus, in one embodiment, n, in the general formula describedabove, ranges from about 20 to about 40. In accordance with certainembodiments of the rubber compositions disclosed herein, the fluorinatedhydrocarbon wax is a fluorinated paraffin wax.

Suitable fluorinated hydrocarbon waxes used in the rubber compositionsdisclosed herein include from about 0.2% to about 70% by weight fluorinebased on the total weight of the wax. In certain embodiments, thefluorinated hydrocarbon wax used includes from about 0.2 to about 12% byweight fluorine or from about 1% to about 8% by weight fluorine.Accordingly, because suitable fluorinated hydrocarbon waxes that areutilized may contain varying amounts of fluorine, it should beunderstood that the total amount of fluorination added to the rubbercomposition can be varied by adjusting the amount (phr) of fluorinatedwax added to the rubber composition and/or the fluorine content of thefluorinated wax added to the rubber composition. Therefore, the totalamount of fluorination added to the rubber composition may vary fromabout 0.0004 phr to about 5 phr (parts fluorine per hundred partsrubber). In certain embodiments, the amount of fluorination added to therubber composition is from about 0.004 to about 1.2 phr, from about 0.04to about 0.6 phr, from about 0.1 to about 0.2.

In other embodiments, the halogenated hydrocarbon wax is a brominatedhydrocarbon wax. Various types of brominated hydrocarbon waxes may besuitable for use in the embodiments disclosed herein, including thosecontaining various weight percentages of bromine such as about 20 toabout 75% by weight based upon the weight of the wax, alternativelyabout 35 about 75% by weight based upon the weight of the wax. In anembodiment, the wax may include both chlorine and bromine and,accordingly, as noted in other portions of this disclosure, it should beconsidered to be within the scope of the disclosure to include acombination of chlorinated hydrocarbon wax and brominated hydrocarbonwax (either as separate waxes or via introduction of one wax containingboth chlorine and bromine).

In certain embodiments, the halogenated hydrocarbon wax is an iodatedwax. Various types of iodated hydrocarbon waxes may be suitable for usein the embodiments disclosed herein, including those containing variousweight percentages of iodine such as about 20 about 75% by weight basedupon the weight of the wax, alternatively about 35 about 75% by weightbased upon the weight of the wax.

In accordance with one embodiment, it is contemplated that thewax-polymer additive may include a combination of at least onefluorinated hydrocarbon wax as disclosed herein and at least onechlorinated hydrocarbon wax.

It was discovered that the wax-polymer additive displays synergisticproperties in rubber compositions filled with silica and carbon black.Different and unexpected properties were seen in a carbon black filledcomposition and a silica filled composition. The examples presentedbelow show these effects.

For example, when the filler comprises carbon black, and the wax-polymeradditive is substituted for at least a portion of processing oil, suchas about 5 phr of oil or less, about 10 to about 15 phr of oil, or about2.5 phr to about 20 phr of oil, the composition may have a Mooneyviscosity (ML1+4, 103° C., RPA) of about 20 to about 60, such as about22 to about 35, or about 25 to about 30. Alternatively, the wax-polymeradditive is substituted for at least a portion of processing oil,leaving only 5 phr or less of oil, or about 2.5 phr to about 10 phr ofoil, or about 12 phr to about 20 phr of oil. The data in the examplesdemonstrates that the wax-polymer additive acts efficiently as an oilreplacement in carbon black filled compositions. In an embodiment, thefiller comprises carbon black and the composition is vulcanized and hasa bound rubber content of about 31% to about 50%, such as about 32% toabout 45% or about 35% to about 40%. This shows that the wax-polymercomposition also increases bound rubber material properties in thevulcanized state while providing oil-like properties in the unvulcanizedstate.

For example, wherein the filler comprises silica and the composition isvulcanized, in an embodiment, the composition has at least about 3%higher (such as about 5% or higher, or about 3% to about 40%) indexedvalue in aged wear resistance over a control composition that is thesame as the composition except it contains the halogenated wax, insteadof the wax-polymer additive derived from the halogenated wax. The agedwear resistance may be determined by Lambourn (25% slip) aged 4 days at50° C. and 95% humidity.

In an embodiment, the wax-polymer compound coats the silica, therebyforming the wax-polymer compound, the wax-polymer compound having anumber average molecular weight of about 1,000 to about 100,000. Thecoating may occur in situ upon mixing the wax-polymer compound with arubber elastomer and silica. Alternatively, the silica may be pre-coatedwith the wax-polymer compound, such as by mixing the dissolvedwax-polymer with silica or a dry mixing process.

Generally, any filler(s) conventionally used to prepare rubbercompositions can be used in the rubber compositions described herein.Examples of suitable fillers used in the rubber compositions disclosedherein include, but are not limited to, reinforcing fillers such ascarbon black; silica; mineral fillers such as clay (e.g., hydrousaluminum silicate), exfoliated clay, talc (hydrous magnesium silicate),aluminum hydrate (Al(OH)₃), and mica; as well as metal oxides such asaluminum oxide; and titanium dioxide. Additional useful fillers suitablefor use in the rubber compositions disclosed herein are known to thoseskilled in the art.

The amount of the at least one filler that is contained within therubber composition is about 5 to about 200 phr, such as, for example,about 20 phr to about 99 phr, or about 45 phr to about 80 phr, wherein amajority of the filler is carbon black, silica or a combination thereof.The amount of carbon black may range, for example, from about 2.5 phr toabout 100 phr, such as about 10 to about 65 phr, or about 20 phr toabout 50 phr. The amount of silica may range, for example, from about2.5 phr to about 120 phr, such as about 20 phr to about 99 phr, or about40 phr to about 70 phr. Additional fillers such as clay, metal oxides,and combinations thereof, may also be included in minority amounts. Inan embodiment, the composition may be exclusive of one of carbon blackor silica, and/or other fillers.

Examples of suitable types of carbon blacks used as the filler incertain embodiments of the tire rubber composition disclosed hereininclude furnace blacks, channel blacks, and lamp blacks. Morespecifically, examples of suitable carbon blacks include super abrasionfurnace (SAF) blacks, high abrasion furnace (HAF) blacks, fast extrusionfurnace (FEF) blacks, fine furnace (FF) blacks, intermediate superabrasion furnace (ISAF) blacks, semi-reinforcing furnace (SRF) blacks,medium processing channel blacks, hard processing channel blacks, andconducting channel blacks. Other examples of suitable carbon blacksinclude, but are not limited to, acetylene blacks. Furthermore, amixture of two or more of the aforementioned carbon blacks can be usedas the filler in certain embodiments of the tire rubber compositiondisclosed herein. The grades of the carbon blacks suitable for use incertain embodiments of the rubber compositions disclosed herein arethose characterized by ASTM D-1765, such as N-110, N-134, N-220, N-339,N-330, N-351, N-550, N-660, and N990 grades. Other grades of carbonblack may also be suitable for use in certain embodiments of the rubbercompositions disclosed herein, either alone, in combination or incombination with the previously listed grades of carbon black.

The carbon blacks used in accordance with embodiments of the tire rubbercomposition disclosed herein can be in a pelletized form or anunpelletized flocculent mass.

Examples of silica used as the filler in certain embodiments of the tirerubber composition disclosed herein include, but are not limited to,precipitated amorphous silicas, dry silicas such as fumed silica, andcalcium silicate. Other suitable fillers include aluminum silicate andmagnesium silicate. In an embodiment, the silica may be treated withadditional agents, such as silane.

The abbreviation “phr,” as used herein, means per hundred rubber, and isbased on the main high molecular weight rubber component of thecomposition.

The rubber compositions disclosed herein include at least one rubberelastomer that is a polymer or copolymer of relatively high molecularweight. The elastomer may, for example, have a number average molecularweight of about 100,000 to about 1,000,000, such as, for example, about150,000 to about 500,000, or about 200,000 to about 350,000. Theelastomer may, for example, may have a polydispersity (Mw/Mn) of about1.1 to about 7, such as about 1.5 to about 5, or about 2 to about 3. Theelastomer may have a glass transition temperature of about −10° C. toabout −115° C., such as about −20° C. to about −55° C., or about −95° C.to about −108° C. If the polymer is a copolymer, it may be random,tapered, or block. If the elastomer is synthetic, it may be made bysolution or emulsion polymerization.

In an embodiment, the elastomer comprises an unsaturated polymer, suchas a conjugated diene polymer or copolymer comprising at least onepolymerized conjugated diene monomer and optionally at least onepolymerized vinyl-containing monomer. Such conjugated diene polymers andconjugated diene copolymers can be derived, for example, from thepolymerization of one or more of the following conjugated diene monomerunits 1,3-butadiene, isoprene, 1,3-pentadiene, 1,3-hexadiene,2,3-dimethyl-1,3-butadiene, 2-ethyl-1,3-butadiene,2-methyl-1,3-pentadiene, 3-methyl-1,3-pentadiene,4-methyl-1,3-pentadiene, 2,4-hexadiene, and combinations thereof.

In certain embodiments, suitable unsaturated polymers and copolymersused in the tire rubber compositions disclosed herein can be derivedfrom the polymerization of one or more of the conjugated diene monomersdisclosed above and one or more vinyl aromatic hydrocarbon monomers.Examples of suitable vinyl aromatic hydrocarbon monomers include, butare not limited to, styrene, α-methylstyrene, p-methylstyrene,o-methylstyrene, p-butylstyrene, vinylnaphthalene, and combinationsthereof.

Examples of suitable unsaturated polymers and copolymers for use as theelastomer in the rubber compositions disclosed herein include, but arenot limited to, polyisoprene, polybutadiene, butadiene-isoprenecopolymer, butadiene-isoprene-styrene copolymer, isoprene-styrenecopolymer, styrene-butadiene copolymer, natural rubber, butyl rubber,halogenated butyl rubber, and combinations thereof. In accordance withthe rubber compositions disclosed herein, the rubber compositionscomprise a combined amount of 100 phr of the at least one elastomericpolymer.

In certain embodiments, the conjugated diene polymer or copolymer (asdescribed above) within the rubber composition is functionalized with afunctional chemical group at one end, both ends, or along the backboneof the polymer or copolymer. In certain embodiments, the conjugateddiene polymer or copolymer is functionalized or coupled with a tin orsilica-containing compound such as with tin tetrachloride, dibutyl tinchloride, or with another suitable compound, non-limiting examples ofwhich include cyclic amines, polyisocyanates, cyclic ureas, a silylchloride, polyisocyanates, carbodiimides, polyepoxides, andalkoxysilanes.

In certain embodiments of the tire rubber composition disclosed herein,a silane coupling agent is used when silica or some other type ofinorganic particles are used as the filler. In such embodiments, thesilane coupling agent helps bond the filler to the conjugated dienepolymer or copolymer (i.e., the elastomer), thereby improving the wearresistance of the vulcanized rubber composition. Examples of suitablesilane coupling agents include, but are not limited to, functionalizedpolysulfide silanes such as bis(trialkoxysilylorgano) polysulfidesilanes and thiocarboxylate functional silanes such as a3-octanoylthio-1-propyltriethoxysilane.

In accordance with certain embodiments, the rubber compositionsdisclosed herein further include a conventional wax and/or processingoil in addition to the wax-polymer additive. However, in otherembodiments, the composition may also be exclusive of an effectiveamount or all of a wax and/or processing oil. An effective amount of waxor oil would be an amount required to produce an antioxidant effect forwax (such as, for example about 0.1 phr or greater, and a viscosityreduction for oil, such as about 3 phr or greater. Examples of suitableconventional waxes for use in the rubber compositions disclosed hereininclude hydrocarbon waxes, such as, for example, microcrystalline waxesand paraffin waxes. In certain embodiments, the conventional waxincludes a microcrystalline wax, a paraffin wax, and combinationsthereof. In accordance with one or more embodiments, the conventionalwax can be added to the rubber composition in an amount of about 0.1 phrto about 10 phr, such as about 1 phr to about 3 phr, or about 0.5 phr toabout 2.5 phr. In accordance with one or more embodiments, theprocessing oil can be added to the rubber composition in an amount ofabout 3 phr to about 50 phr, such as about 5 phr to about 35 phr, orabout 10 phr to about 20 phr.

The rubber compositions disclosed herein include a curative package. Inaccordance one or more embodiments, a curative package includes at leastone vulcanizing agent and optionally any of: vulcanizing accelerators;vulcanizing activators, such as zinc oxide and stearic acid; vulcanizinginhibitor; and anti-scorch agents. A “vulcanizing agent” refers to thecompounds used alone, or as part of a system, to cure, i.e., crosslink,the rubber composition during vulcanization. In certain embodiments, thecurative package includes at least one vulcanizing agent and at leastone vulcanizing accelerator. In other embodiments, the curative packageincludes at least one vulcanizing agent, at least one vulcanizingaccelerator, and at least one vulcanizing activator. In yet otherembodiments, the curative package includes at least one vulcanizingagent, at least one vulcanizing accelerator, at least one vulcanizingactivator, and at least one vulcanizing inhibitor. In still otherembodiments, the curative package includes at least one vulcanizingagent, at least one vulcanizing accelerator, at least one vulcanizingactivator, at least one vulcanizing inhibitor, and at least oneanti-scorching agent.

Examples of suitable types of vulcanizing agents used in the rubbercompositions disclosed herein, include but are not limited to, sulfur orperoxide-based curing systems. Examples of specific suitable sulfurvulcanizing agents used in the rubber compositions disclosed hereininclude “rubbermaker's” soluble sulfur; sulfur donating curing agents,such as an amine disulfide, polymeric polysulfide or sulfur olefinadducts; and insoluble polymeric sulfur. In an embodiment, the sulfurvulcanizing agent is soluble sulfur or a mixture of soluble andinsoluble polymeric sulfur. For a general disclosure of suitablevulcanizing agents, one can refer to Kirk-Othmer, Encyclopedia ofChemical Technology, 3rd ed., Wiley Interscience, N.Y. 1982, Vol. 20,pp. 365 to 468, particularly Vulcanization Agents and AuxiliaryMaterials, pp. 390 to 402, or Vulcanization by A. Y. Coran, Encyclopediaof Polymer Science and Engineering, Second Edition (1989 John Wiley &Sons, Inc.), both of which are incorporated herein by reference.Vulcanizing agents can be used alone or in combination. In anembodiment, a vulcanizing agent that produces a sulfidic bridgecrosslink is utilized. The sulfur vulcanizing agents are used in anamount ranging from about 0.1 to about 10 phr, about 0.2 to about 7.5phr, or about 0.2 to about 5 phr.

Vulcanizing accelerators are used to control the time and/or temperaturerequired for vulcanization and to improve properties of the vulcanizate.Examples of suitable vulcanizing accelerators used in the rubbercompositions disclosed herein include, but are not limited to, thiazolevulcanization accelerators, such as 2-mercaptobenzothiazole,2,2′-dithiobis(benzothiazole) (MBTS),N-cyclohexyl-2-benzothiazole-sulfenamide (CBS),N-tert-butyl-2-benzothiazole-sulfenamide (TBBS); guanidine vulcanizationaccelerators, such as diphenyl guanidine (DPG); thiuram vulcanizingaccelerators; carbamate vulcanizing accelerators. The amount of thevulcanization accelerator used ranges from about 0.1 to about 7 phr,about 0.2 to about 5 phr, or about 0.5 phr to about 3 phr.

As mentioned above, process oils can be used to extend and soften therubber compositions disclosed herein. The wax-polymer additive, in someembodiments, allows for replacement of a part or all of the oil of atypical composition. In embodiments that contain processing oil inaddition to the polymer—wax additive, the processing oil includes but isnot limited to, paraffinic oils, aromatic oils, naphthenic oils,vegetable oils other than castor oils, and low polycyclic aromaticcontent (“low PCA”) oils. Low PCA oils are oils that contain less than 3weight percent polycyclic aromatic content (as measured by IP346).Examples of such low PCA oils useful for the rubber compositionsdisclosed herein include various naphthenic oils, mild extractionsolvates (MES) and treated distillate aromatic extracts (TDAE).

Other additives that can be used in the rubber compositions disclosedherein are also well known to those of skill in the art and includeresins, such as tackifying resins; reinforcing resins; plasticizers;pigments; zinc oxide; antioxidants such as diphenyl-p-phenylenediamine(DPPD), N-(1,3-dimethylbutyl)-N″-phenyl-1,4-benzenediamine (6PPD);anti-ozonants; peptizing agents; recycled crumb rubber; and asphalt. Ina particular embodiment, the composition is free of asphalt.

The rubber compositions disclosed herein are useful for differentcomponents of a pneumatic tire, including, but not limited to, treads,subtreads, sidewalls, bead fillers, carcass layers, sidewallreinforcements, and run-flat reinforcements.

The rubber compositions disclosed herein can be prepared using standardequipment such as, e.g., Banbury or Brabender mixers. For furtherexplanation of rubber compounding and the additives conventionallyemployed, one can refer to The Compounding and Vulcanization of Rubber,by Stevens in Rubber Technology, Second Edition (1973 Van NostrandReibold Company), which is incorporated herein by reference. Typically,the rubber compositions disclosed herein are prepared using two or moremixing stages. During the first stage (also known as the “master batch”stage), ingredients including the rubber components and fillers aremixed. The mixing during this stage typically occurs at temperatures ofabout 100° C. to about 200° C. for a period of time or until a dischargeor drop temperature, typically about 165° C., is reached. To preventpremature vulcanization (also known as scorch), this initial masterbatchmay exclude any vulcanizing agents or other components of the curativepackage.

For certain rubber compositions such as where a formulation includeshigher amounts of filler or fillers other than (or in addition to)carbon black, a separate re-mill stage may be employed for separateaddition of the other fillers in order to reduce the compound viscosityand improve the dispersion of the fillers. This stage often is performedat temperatures similar to, although often slightly lower than, thoseemployed in the master batch stage.

Most or all of the components of the curative package, e.g., vulcanizingagents, vulcanizing accelerators, vulcanizing activators, etc., aregenerally added at a final mixing stage. To avoid undesirable scorchingand/or premature onset of vulcanization, this mixing step often is doneat lower temperatures, e.g., starting at about 60° C. to about 75° C.and not going higher than about 105° C. to about 110° C. As referred toherein, the term “final batch” means the composition that is presentduring the final mixing stage. Typically, when the rubber compositionsare to be used in tires, vulcanization is effected by heating thevulcanizable composition in a mold under pressure. Pneumatic tires canbe made as disclosed in U.S. Pat. Nos. 5,866,171, 5,876,527, 5,931,211,and 5,971,046, which are incorporated herein by reference.

Depending upon the ultimate use for the rubber composition, it may beprocessed (e.g., milled) into sheets prior to being formed into any of avariety of components and then vulcanized, which typically occurs atabout 5° C. to about 15° C. higher than the highest temperaturesemployed during the mixing stages, most commonly about 170° C.

EXAMPLES

The halogenated wax used in the examples below was a chlorinatedparaffin wax that was solid at 25° C. It had a chlorine wt. percent of71% based on the total weight of the wax and a softening point of 103°C. (ASTM D-36) and a melting point of 70.2° C. The halogenated wax had aparticle size corresponding to a 95% pass through a 297 Micron mesh anda molecular weight 1160 g/mol.

The rubber compounding examples below were performed with the followingprocedures. Polymer, filler, coupling agent (when present), oil,antioxidant, stearic acid, and a wax or grafted wax ingredient wereadded in a masterbatch stage in a Brabender mixer. The mixing speedincreased to 90 RPM during the time period of 30 sec to 4.5 min. Themaster-batched polymers were dropped around 165° C. at 5.5 min of mixingtime. The final batch was completed by adding sulfur, zinc oxide, andaccelerators and dropping around 105° C. at 2.5 min of mixing time.

Lambourn abrasion testing is performed as follows. Test specimens areplaced on an axle and run at various slip angles and speeds, against adriven abrasive surface. Dry talc powder (100 series) is used as alubricant and is supplied by a metering system. The test specimen isweighed before testing and after testing to determine the amount ofmaterial loss. Test specimen geometry is circular with the followingapproximate dimensions: inside diameter=0.900 inch (22.86 mm), outsidediameter=1.900 inch (48.26 mm), thickness=0.195 inch (4.95 mm). The testsurface is 3M 120-grit psa paper on an aluminum wheel. The machine waswarmed up at least 30 minutes prior to testing. An air supply at 0.5-psiis used to disperse talc to a fine dust form. Additional machinesettings are: thumbwheel type, sample speed set 34 (all slips), 200 rpm.Drum speed set: 24 (25% slip) and 12 (65% slip). Test settings are 25%slip—test time of 90 to 180 seconds, and talc setting of 0.6; 65%slip—test time of 25 to 60 seconds, talc setting of 1.

Bound rubber testing is measured by immersing small pieces (about ⅛ inchdiameter) of uncured compounded rubber stocks (approximately 0.2 gramsof the compounded stock)) in an aluminum sample cylinder with 40 meshstainless steel screen. The sample cylinder is placed in a sealedcontainer with 100 mL of toluene solvent. After three days the remainingsample is removed from the solvent and thoroughly dried. The remainingpieces form a weak coherent gel containing the filler and some of theoriginal rubber. The amount of rubber remaining with the filler isweighed and is the bound rubber. % Bound rubber is calculated asfollows:

% Bound rubber=(100(Wd−F))/R

Wd=weight of dried gel

F=weight of filler in gel or solvent insoluble matter

(same as weight of filler in original sample)

R=weight of polymer in original sample

Example 1: Synthesis of Chlorinated Wax Grafted with SBR

In Example 1, 13.3 g of styrene (34 wt % in hexane), 85.6 g of butadiene(22.6 wt % in hexane), and 300 g hexane were charged to a 0.8 Literbottle sealed and purged with nitrogen. To the bottle was charged 7 mlof butyl lithium (1.60 M in hexane) and 3 ml of2,2′-di(tetrahydrofuryl)propane (1.6 M in hexane). After stirringapproximately 100 minutes at room temperature, 1 ml of2,2′-di(tetrahydrofuryl)propane and 30 ml of the halogenated wax (8.3%in tetrahydrofuran (THF)) were added to the bottle. The bottle contentswere then terminated with 9 ml of butylated hydroxytoluene (BHT) inisopropanol, coagulated with ethanol and dried under vacuum. Theisolated wax grafted with SBR polymer had the following properties:Mn=3.8 kg/mol, Mw=5.1 kg/mol, MWD=1.35, Tg=−24.67° C., styrene 20.4%,vinyl=58.6%, Cl=0.4%.

Example 2: Synthesis of Chlorinated Wax Grafted with SBR

In Example 2, 17.08 g of styrene (34 wt % in hexane), 109.6 g ofbutadiene (22.6 wt % in hexane), and 186 g hexane were charged to a 0.8Liter bottle sealed and purged with nitrogen. To the bottle was charged9.07 ml of butyl lithium (1.60 M in hexane) and 4.46 ml of2,2′-di(tetrahydrofuryl)propane (1.6 M in hexane). After stirringapproximately 80 minutes at room temperature, 1 ml of2,2′-di(tetrahydrofuryl)propane and 30 ml of halogenated wax (8.3% inTHF) were added to the bottle. The bottle contents were then terminatedwith 9 ml of BHT in isopropanol, coagulated with ethanol and dried undervacuum. The isolated polymer had the following properties: Mn=3.9kg/mol, Mw=5.4 kg/mol, MWD=1.38, Tg=−24.67° C., styrene 22.4%,vinyl=56%, and Cl=0.28%.

Example 3: Synthesis of Chlorinated Wax Grafted with SBR

In Example 3, 26.7 g of styrene (34 wt % in hexane), 171.7 g ofbutadiene (22.6 wt % in hexane) and 206 g hexane were charged to a 0.8Liter bottle sealed and purged with nitrogen. To the bottle was charged14.2 ml of butyl lithium (1.60 M in hexane) and 7 ml of2,2′-di(tetrahydrofuryl)propane (1.6 M in hexane). After stirringapproximately 60 minutes at room temperature, 1 ml of2,2′-di(tetrahydrofuryl)propane and 30 ml of the halogenated wax (8.3%in THF) were added to the bottle. The bottle contents were thenterminated with 9 ml of BHT in isopropanol, coagulated with ethanol anddried under vacuum. The isolated polymer had the following properties:Mn=4.1 kg/mol, Mw=5.9 kg/mol, MWD=1.43, Tg=−26.45° C., styrene 22.2%,vinyl=55%, and Cl=0.2%.

Example 4: Synthesis of Chlorinated Wax Grafted with SBR

In Example 4, 13.3 g of styrene (34 wt % in hexane) and 85.6 g ofbutadiene (22.6 wt % in hexane) and 210 g hexane were charged to a 0.8Liter bottle sealed and purged with nitrogen. To the bottle was charged7 ml of butyl lithium (1.60 M in hexane) and 3 ml of2,2′-di(tetrahydrofuryl)propane (1.6 M in hexane). After stirringapproximately 90 minutes at room temperature, 1 ml of2,2′-di(tetrahydrofuryl)propane and 30 ml of the halogenated wax (8.3%in THF) were added to the bottle. The bottle contents were thenterminated with 9 ml of BHT in isopropanol, coagulated with ethanol anddried under vacuum. The isolated polymer had the following properties:Mn=4.0 kg/mol, Mw=5.2 kg/mol, MWD=1.35, Tg=−30.71° C., styrene 20.1%,vinyl=57.8%, and Cl=0.1%.

Three SBR-grafted Cl-waxes, from Examples 1-3 above, were characterizedas shown in Table 1.

TABLE 1 GPC M_(z)(k_(g)/ M_(n) M_(w) M_(w)/ ¹H-NMR (mol %) T_(g) Wax-SBRmol) k_(g)/mol) (k_(g)/mol) M_(n) Styrene Vinyl 1, 4% Cl % (° C.)SBR-polymer 2.6 2.0 2.3 1.16 n/a n/a n/a n/a n/a brush, prior to waxgrafting Example 1 7.0 3.8 5.1 1.35 11.6 64.3 23.3 0.4 −24.67 Example 27.4 3.9 5.4 1.38 13.0 62.6 24.1 0.3 −25.38 Example 3 8.4 4.1 5.9 1.4312.9 61.4 25.5 0.2 −26.45 Example 4 n/a 4.0 5.2 1.35 20.1 57.8 22.1 0.1−30.71

Examples 5-8: Characterization and Carbon Black Filled CompoundingEvaluation of SBR-Grafted Cl-Waxes as an Oil Replacement

In Examples 6-8, the wax-polymer additive of Examples 1-3 was mixed witha styrene-butadiene rubber, carbon black, oil, and other rubbercomposition additives and vulcanized with sulfur as shown in Table 2.Example 5 is a control that has a full loading of oil but no wax-polymeradditive. Examples 5-9 replace 18 parts of the oil with an equal part ofthe wax-polymer additive.

TABLE 2 Example 5 6 7 8 SBR (Mn 108 kg/mol, Mw 323 kg/mol 100 100 100100 styrene 20%, vinyl 55%) Oil (hydrotreated, heavy-naphthenic, 37.519.5 19.5 19.5 low-PCA oil) Carbon black 75 75 75 75 Stearic acid 2 2 22 Antioxidant 1 1 1 1 Example 1 18 Example 2 18 Example 3 18 Zinc oxide3 3 3 3 MBTS 1 1 1 1 DPG 0.5 0.5 0.5 0.5 Sulfur 1.5 1.5 1.5 1.5

Table 3 shows the compound properties of Examples 5-8 showing the effectof the partial oil replacement. The SBR-grafted Cl-wax as an oilreplacement increased bound rubber without trade-off of compound Mooney.In fact, the Mooney viscosity was reduced in all examples 6-8. Themodified Cl-wax enhanced compound modulus with higher tan δ @ 0° C. andlower tan δ @ 50° C.

TABLE 3 Composition Example No. 5 6 7 8 Wax-polymer Example No. none 1 23 Bound rubber (%) 30.8 34.5 35.3 36.0 T5 3.33 2.87 2.86 3.19 T90 10.8811.18 11.46 12.22 ML1 + 4 (130° C., RPA) 40 38 39 37 (pre-vulcanization)Shore A  23° C. 57.3 60.5 61.5 61.6 100° C. 50.8 55.0 55.5 55.5 STRAINSWEEP (0° C.) G′ (MPa) @ 5%, 10 Hz: 5.848 7.635 7.471 7.316 G″ (MPa) @5%, 10 Hz: 3.757 5.656 5.569 5.373 tanδ @ 5%, 10 Hz: 0.642 0.741 0.7450.734 STRAIN SWEEP (50° C.) G′ (MPa) @ 5%, 15 Hz: 2.430 2.686 2.5952.524 G″ (MPa) @ 5%, 15 Hz: 0.675 0.701 0.699 0.669 tanδ @ 5%, 15 Hz:0.278 0.261 0.269 0.265 ΔG′ (MPa) [0.25-14%], 15 Hz: 3.341 3.039 3.0152.781 Tensile (Dumbell 23° C. unaged) 50% Modulus (MPa) 1.420 1.6961.673 1.759 300% Modulus (MPa) 10.719 12.300 12.885 12.861 TB (MPa) 13.513.4 13.0 12.8 EB (%) 371 325 308 301

Examples 9-14 Evaluation of SBR-Grafted Halogenated Wax as a WaxReplacement in Carbon Black Filled Composition

Table 4 shows carbon black-filled rubber formulation for evaluatingthree different waxes: tire wax, the halogenated wax described above,and the wax-polymer additive of Example 4.

TABLE 4 Example 9 10 11 12 13 14 SBR1 (Mn 108 kg/mol, Mw 100 100 100 323kg/mol, styrene 25%, vinyl 13%, Tg = −64° C.) SBR2 (Mn 258 kg/mol, Mw100 100 100 424 kg/mol, styrene 21%, vinyl 60%, T_(g) = −28.9° C.) Oil10 10 10 10 10 10 Carbon black 50 50 50 50 50 50 Stearic acid 2 2 2 2 22 Antioxidant 1 1 1 1 1 1 Microcrystalline tire wax* 2 2 Example 4wax-polymer additive 3.5 3.5 Halogenated wax 3.5 3.5 Zinc oxide 2.5 2.52.5 2.5 2.5 2.5 DPG 0.3 0.3 0.3 0.3 0.3 0.3 MBTS 0.5 0.5 0.5 0.5 0.5 0.5TBBS 0.5 0.5 0.5 0.5 0.5 0.5 Sulfur 1.5 1.5 1.5 1.5 1.5 1.5 *Only 2 phrof microcrystalline wax was used to try and approximate the same numberof carbon atoms in the chlorinated wax. The polymer-modified Cl-wax hada much lower molar ratio due to its higher molecular weight imparted bythe Chlorine atoms.

Table 5 shows the compound properties of the Example 9-14 rubbercompounds. Replacing tire wax and chlorinated wax, the wax-polymeradditive enhanced wet traction and improved wear resistance uponhumidity aging. It also provided reduced compound Mooney viscosity.

TABLE 5 Example 9 10 11 12 13 14 Wax Micro- Ex. 4 Halogenated Micro- Ex.4 Halogenated crystalline wax crystalline wax ML1 + 4 (130° C.) (pre-43.5 43.1 43.8 43.7 43 46.6 vulcanization) 0° C. K′ (lbf/in): 297.248256.817 290.112 333.027 250.607 275.704 K″ (lbf/in): 71.466 62.01765.391 174.731 110.099 113.264 tanδ: 0.240 0.241 0.225 0.521 0.437 0.411Rebound 50.0 50.4 51.0 52.8 52.4 51.6 Wet Unaged 39 39 39 46 46 45.8Stanley aged, 4 days 39 39 39 46 46 45.8 @50° C., 95% humidity Lambournaged, 4 days 100 92 61 100 103 70 (25% slip) @50° C., 95% humidity

Example 15 Synthesis of Chlorinated Wax Grafted with SBR

13.3 g of styrene (34 wt % in hexane), 85.6 g of butadiene (22.6 wt % inhexane), and 210 g hexane were charged to a 0.8 Liter bottle sealed andpurged with nitrogen. To the bottle was charged 7 ml of butyl lithium(1.60 M in hexane) and 3 ml of 2,2′-di(tetrahydrofuryl)propane (1.6 M inhexane). After stirring approximately 80 minutes at room temperature, 1ml of 2,2′-di(tetrahydrofuryl)propane and 30 ml of halogenated wax (8.3%in THF) were added to the bottle. The bottle contents were thenterminated with 9 ml of BHT in isopropanol, coagulated with ethanol anddried under vacuum. The isolated polymer had the following properties:Mn=4.0 kg/mol, Mw=5.4 kg/mol, MWD=1.33, T=−−26.88° C., Styrene 19.5%,Vinyl=58.2%, Cl=0.11%.

Examples 16-21 Evaluation of SBR-Grafted Cl-Waxes as a Wax Replacementin Silica-Filled Compositions

Table 6 shows silica-filled rubber formulations for evaluating tire wax,the halogenated wax described above, and SBR-grafted Cl-wax of Example15 (which was derived from the halogenated wax).

TABLE 6 Silica-filled compounding formulation Example 16 17 18 19 20 21SBR1 (Mn 108 kg/mol, Mw 323 100 100 100 kg/mol, styrene 25%, vinyl 13%,Tg = −64° C.) SBR2 (Mn 258 kg/mol, Mw 424 100 100 100 kg/mol, styrene21%, vinyl 60%, T_(g) = −28 .9° C.) Oil 10 10 10 10 10 10 Silica 52.552.5 52.5 52.5 52.5 52.5 Stearic acid 2 2 2 2 2 2 Antioxidant 1 1 1 1 11 Tire wax 2 2 Halogenated wax 3.5 3.5 Example 15 wax-polymer 3.5 3.5additive Silica 2.5 2.5 2.5 2.5 2.5 2.5 Silane 5 5 5 5 5 5 Zinc oxide2.5 2.5 2.5 2.5 2.5 2.5 TBBS 0.7 0.7 0.7 0.7 0.7 0.7 MBTS 2 2 2 2 2 2DPG 1.4 1.4 1.4 1.4 1.4 1.4 Sulfur 1.5 1.5 1.5 1.5 1.5 1.5

Table 7 shows compound properties of the rubber compounds in the absenceand presence of the waxes.

TABLE 7 Example 16 17 18 19 20 21 Bound rubber % 23.9 25.6 25.7 28.929.1 29.3 ML1 + 4 (130° C.) 47.5 48.9 46.6 47.4 49.1 46.8  0° C. K′(lbf/in): 514.921 486.100 431.475 642.384 683.998 624.356 K″ (lbf/in):92.151 84.032 79.422 234.346 263.764 299.893 Tanδ: 0.179 0.173 0.1840.364 0.385 0.478 60° C. K′ (lbf/in): 274.431 309.177 265.230 273.819283.926 259.188 K″ (lbf/in): 34.488 39.893 33.612 21.135 24.850 21.103Tanδ: 0.126 0.129 0.127 0.077 0.088 0.081 Rebound 54.8 51.6 53.6 52.250.4 51.0 Lambourn Aged, 4 days @50° C., 102 77 108 172 64 189 (25%slip) 95% humidity Wet Unaged 36.3 40.8 44.8 39 41 42 Stanley Aged, 4days @50° C., 41 44 44 48.5 51.5 51.2 95% humidity

Comparing the controls with and without tire wax or chlorinated wax, thewax-polymer additive reduced compound Mooney and increased tan δ at 0°C. with comparable or lower tan δ at 60° C. The results of Wet Stanleyalso indicated enhancement of wet traction in Examples 18 and 21, whichcontained the wax-polymer additive in comparison to those that containedtire wax or Cl-wax. Examples 18 and 21 also showed significantly betterwear resistance upon humidity aging than the unmodified Cl-wax.

To the extent that the term “includes” or “including” is used in thespecification or the claims, it is intended to mean “comprising.”Furthermore, to the extent that the term “or” is employed, unless thecontext clearly indicates to the contrary, it is intended to be anon-exclusive “or”, i.e., “A or B or both.” As used in the descriptionand the claims, the terms “a,” “an,” and “the” mean “one or more” unlessthe context clearly indicates otherwise.

While the present application has been illustrated by the description ofembodiments thereof, and while the embodiments have been described inconsiderable detail, it is not the intention of the applicants torestrict or in any way limit the scope of the appended claims to suchdetail. Additional advantages and modifications will readily appear tothose skilled in the art. Therefore, the application, in its broaderaspects, is not limited to the specific details, the representativeapparatus, and illustrative examples shown and described. Accordingly,departures may be made from such details without departing from thespirit or scope of the applicant's general inventive concept.

All references incorporated herein by reference are incorporated intheir entirety unless otherwise stated.

It is claimed:
 1. A tire component comprising: a rubber elastomercomprising a polymerized unsaturated monomer and optionally apolymerized vinyl-aromatic monomer, the elastomer having a numberaverage molecular weight of about 100,000 to about 1,000,000; a fillerin an amount of about 5 to about 200 phr, the filler comprising carbonblack, silica, or both; and a wax-polymer additive that includes: (a) apolymer component that is a polymerized unsaturated monomer, optionallycopolymerized with a vinyl-aromatic monomer, and (b) a halogenatedhydrocarbon wax component; the polymer component being grafted to thehalogenated hydrocarbon wax component, the wax-polymer additive having anumber average molecular weight of about 1,000 to about 100,000.
 2. Thetire component of claim 1, wherein the filler comprises silica.
 3. Thetire component of claim 1, wherein the tire component is a tire tread.4. The tire component of claim 1, wherein the halogenated hydrocarbonwax component is a solid at 0° C.
 5. The tire component of claim 1,wherein number average molecular weight of the polymer component isabout 500 to about 20,000.
 6. The tire component of claim 1, wherein thewax component comprises a branched or unbranched C₂₀ to C₄₀ alkane wax.7. The tire component of claim 1, wherein the polymer component isgrafted to the halogenated hydrocarbon wax component at more than onegraft location.
 8. The tire component of claim 1, wherein thehalogenated hydrocarbon wax component is halogenated along a hydrocarbonchain backbone of the wax.
 9. The tire component of claim 1, wherein therubber elastomer comprises a styrene-butadiene rubber.
 10. The tirecomponent of claim 1, wherein the polymer component is copolymerizedwith the vinyl-aromatic monomer.
 11. The tire component of claim 1,further comprising about 5 phr or less of processing oil and the fillerincludes carbon black, wherein the composition has a Mooney viscosity(ML1+4, 103° C., RPA) of about 20 to about
 60. 12. The tire component ofclaim 1, wherein the filler includes carbon black, and the tirecomponent has a bound rubber content of about 31% to about 50%.
 13. Amethod for making a composition comprising: mixing: a rubber elastomercomprising a polymerized unsaturated monomer and optionally apolymerized vinyl-aromatic monomer, the elastomer having a numberaverage molecular weight of about 100,000 to about 1,000,000; a fillerin an amount of about 5 to about 200 phr, the filler comprising carbonblack, silica, or both; a wax-polymer additive that includes: (a) apolymer component that is a polymerized unsaturated monomer, optionallycopolymerized with a vinyl-aromatic monomer, and (b) a halogenatedhydrocarbon wax component, the polymer component grafted to thehalogenated hydrocarbon wax component, the wax-polymer additive having anumber average molecular weight of about 1,000 to about 100,000; andcuring the composition.
 14. The method of claim 13, wherein thehalogenated hydrocarbon wax component is present in a ratio with thepolymer component in a range of about 1:1 to about 1:20.
 15. The methodof claim 13, wherein the polymer component comprises two or more polymerchains that are bonded to a single halogenated hydrocarbon wax.
 16. Themethod of claim 13, wherein the rubber elastomer comprises astyrene-butadiene rubber.
 17. The method of claim 13, wherein the curingstep comprises vulcanizing.
 18. The method of claim 13, wherein thefiller comprises silica.
 19. The method of claim 13, wherein the polymercomponent is polymerized in the same container as the mixing of thewax-polymer compound.
 20. A coated silica compound comprising: silicacoated with a wax-polymer compound, the wax-polymer compound comprising:(a) a polymer component that is a polymerized unsaturated monomer,optionally copolymerized with a vinyl-aromatic monomer, and (b) ahalogenated hydrocarbon wax component; the polymer component grafted tothe halogenated hydrocarbon wax component, the wax-polymer compoundhaving a number average molecular weight of about 1,000 to about100,000.